#!/usr/bin/env zsh

##############################
# CHANGELOG SCRIPT CONSTANTS #
##############################

#* Holds the list of valid types recognized in a commit subject
#* and the display string of such type
local -A TYPES
TYPES=(
  BUILD     "Build system"
  CHORE     "Chore"
  CI        "CI"
  CUT       "Features removed"
  DOC       "Documentation"
  FEAT      "Features"
  FIX       "Bug fixes"
  LICENSE   "License update"
  MAKE      "Build system"
  OPTIMIZE  "Code optimization"
  PERF      "Performance"
  REFACTOR  "Code Refactoring"
  REFORMAT  "Code Reformating"
  REVERT    "Revert"
  TEST      "Testing"
)

#* Types that will be displayed in their own section,
#* in the order specified here.
local -a MAIN_TYPES
MAIN_TYPES=(FEAT FIX PERF REFACTOR DOCS DOC)

#* Types that will be displayed under the category of other changes
local -a OTHER_TYPES
OTHER_TYPES=(MAKE TEST STYLE CI OTHER)

#* Commit types that don't appear in $MAIN_TYPES nor $OTHER_TYPES
#* will not be displayed and will simply be ignored.


############################
# COMMIT PARSING UTILITIES #
############################

function parse-commit {

  # This function uses the following globals as output: commits (A),
  # subjects (A), scopes (A) and breaking (A). All associative arrays (A)
  # have $hash as the key.
  # - commits holds the commit type
  # - subjects holds the commit subject
  # - scopes holds the scope of a commit
  # - breaking holds the breaking change warning if a commit does
  #   make a breaking change

  function commit:type {
    local commit_message="$1"
    local type="$(sed -E 's/^([a-zA-Z_\-]+)(\(.+\))?!?: .+$/\1/' <<< "$commit_message"| tr '[:lower:]' '[:upper:]')"
    # If $type doesn't appear in $TYPES array mark it as 'other'
    if [[ -n "${(k)TYPES[(i)${type}]}" ]]; then
      echo $type
    else
      echo other
    fi
  }

  function commit:scope {
    local scope

    # Try to find scope in "type(<scope>):" format
    # Scope will be formatted in lower cases
    scope=$(sed -nE 's/^[a-zA-Z_\-]+\((.+)\)!?: .+$/\1/p' <<< "$1")
    if [[ -n "$scope" ]]; then
      echo "$scope" | tr '[:upper:]' '[:lower:]'
      return
    fi

    # If no scope found, try to find it in "<scope>:" format
    # Make sure it's not a type before printing it
    scope=$(sed -nE 's/^([a-zA-Z_\-]+): .+$/\1/p' <<< "$1")
    if [[ -z "${(k)TYPES[(i)$scope]}" ]]; then
      echo "$scope"
    fi
  }

  function commit:subject {
    # Only display the relevant part of the commit, i.e. if it has the format
    # type[(scope)!]: subject, where the part between [] is optional, only
    # displays subject. If it doesn't match the format, returns the whole string.
    sed -E 's/^[a-zA-Z_\-]+(\(.+\))?!?: (.+)$/\2/' <<< "$1"
  }

  # Return subject if the body or subject match the breaking change format
  function commit:is-breaking {
    local subject="$1" body="$2" message

    if [[ "$body" =~ "BREAKING CHANGE: (.*)" || \
      "$subject" =~ '^[^ :\)]+\)?!: (.*)$' ]]; then
      message="${match[1]}"
      # remove CR characters (might be inserted in GitHub UI commit description form)
      message="${message//$'\r'/}"
      # skip next paragraphs (separated by two newlines or more)
      message="${message%%$'\n\n'*}"
      # ... and replace newlines with spaces
      echo "${message//$'\n'/ }"
    else
      return 1
    fi
  }

  # Return truncated hash of the reverted commit
  function commit:is-revert {
    local subject="$1" body="$2"

    if [[ "$subject" = Revert* && \
      "$body" =~ "This reverts commit ([^.]+)\." ]]; then
      echo "${match[1]:0:7}"
    else
      return 1
    fi
  }

  # Parse commit with hash $1
  local hash="$1" subject body warning rhash
  subject="$(command git show -s --format=%s $hash)"
  body="$(command git show -s --format=%b $hash)"

  # Commits following Conventional Commits (https://www.conventionalcommits.org/)
  # have the following format, where parts between [] are optional:
  #
  #  type[(scope)][!]: subject
  #
  #  commit body
  #  [BREAKING CHANGE: warning]

  # commits holds the commit type
  commits[$hash]="$(commit:type "$subject")"
  # scopes holds the commit scope
  scopes[$hash]="$(commit:scope "$subject")"
  # subjects holds the commit subject
  subjects[$hash]="$(commit:subject "$subject")"

  # breaking holds whether a commit has breaking changes
  # and its warning message if it does
  if warning=$(commit:is-breaking "$subject" "$body"); then
    breaking[$hash]="$warning"
  fi

  # reverts holds commits reverted in the same release
  if rhash=$(commit:is-revert "$subject" "$body"); then
    reverts[$hash]=$rhash
  fi
}

#############################
# RELEASE CHANGELOG DISPLAY #
#############################

function display-release {

  # This function uses the following globals: output, version,
  # commits (A), subjects (A), scopes (A), breaking (A) and reverts (A).
  #
  # - output is the output format to use when formatting (raw|text|md)
  # - version is the version in which the commits are made
  # - commits, subjects, scopes, breaking, and reverts are associative arrays
  #   with commit hashes as keys

  # Remove commits that were reverted
  local hash rhash
  for hash rhash in ${(kv)reverts}; do
    if (( ${+commits[$rhash]} )); then
      # Remove revert commit
      unset "commits[$hash]" "subjects[$hash]" "scopes[$hash]" "breaking[$hash]"
      # Remove reverted commit
      unset "commits[$rhash]" "subjects[$rhash]" "scopes[$rhash]" "breaking[$rhash]"
    fi
  done

  # If no commits left skip displaying the release
  if (( $#commits == 0 )); then
    return
  fi

  ##* Formatting functions

  # Format the hash according to output format
  # If no parameter is passed, assume it comes from `$hash`
  function fmt:hash {
    #* Uses $hash from outer scope
    local hash="${1:-$hash}"
    case "$output" in
    raw) printf "$hash" ;;
    text) printf "\e[33m$hash\e[0m" ;; # red
    md) printf "[\`$hash\`](https://github.com/aristanetworks/ansible-avd/commit/$hash)" ;;
    esac
  }

  # Format headers according to output format
  # Levels 1 to 2 are considered special, the rest are formatted
  # the same, except in md output format.
  function fmt:header {
    local header="$1" level="$2"
    case "$output" in
    raw)
      case "$level" in
      1) printf "$header\n$(printf '%.0s=' {1..${#header}})\n\n" ;;
      2) printf "$header\n$(printf '%.0s-' {1..${#header}})\n\n" ;;
      *) printf "$header:\n\n" ;;
      esac ;;
    text)
      case "$level" in
      1|2) printf "\e[1;4m$header\e[0m\n\n" ;; # bold, underlined
      *) printf "\e[1m$header:\e[0m\n\n" ;; # bold
      esac ;;
    md) printf "$(printf '%.0s#' {1..${level}}) $header\n\n" ;;
    esac
  }

  function fmt:scope {
    #* Uses $scopes (A) and $hash from outer scope
    local scope="${1:-${scopes[$hash]}}"

    # Get length of longest scope for padding
    local max_scope=0 padding=0
    for hash in ${(k)scopes}; do
      max_scope=$(( max_scope < ${#scopes[$hash]} ? ${#scopes[$hash]} : max_scope ))
    done

    # If no scopes, exit the function
    if [[ $max_scope -eq 0 ]]; then
      return
    fi

    # Get how much padding is required for this scope
    padding=$(( max_scope < ${#scope} ? 0 : max_scope - ${#scope} ))
    padding="${(r:$padding:: :):-}"

    # If no scope, print padding and 3 spaces (equivalent to "[] ")
    if [[ -z "$scope" ]]; then
      printf "${padding}   "
      return
    fi

    # Print [scope]
    case "$output" in
    raw|md) printf "[$scope]${padding} " ;;
    text) printf "[\e[38;5;9m$scope\e[0m]${padding} " ;; # red 9
    esac
  }

  # If no parameter is passed, assume it comes from `$subjects[$hash]`
  function fmt:subject {
    #* Uses $subjects (A) and $hash from outer scope
    local subject="${1:-${subjects[$hash]}}"

    # Capitalize first letter of the subject
    subject="${(U)subject:0:1}${subject:1}"

    case "$output" in
    raw) printf "$subject" ;;
    # In text mode, highlight (#<issue>) and dim text between `backticks`
    text) sed -E $'s|#([0-9]+)|\e[32m#\\1\e[0m|g;s|`([^`]+)`|`\e[2m\\1\e[0m`|g' <<< "$subject" ;;
    # In markdown mode, link to (#<issue>) issues
    md) sed -E 's|#([0-9]+)|[#\1](https://github.com/aristanetworks/ansible-avd/issues/\1)|g' <<< "$subject" ;;
    esac
  }

  function fmt:type {
    #* Uses $type from outer scope
    local type="${1:-${TYPES[$type]:-${(C)type}}}"
    [[ -z "$type" ]] && return 0
    case "$output" in
    raw|md) printf "$type: " ;;
    text) printf "\e[4m$type\e[24m: " ;; # underlined
    esac
  }

  ##* Section functions

  function display:version {
    fmt:header "$version" 2
  }

  function display:breaking {
    (( $#breaking != 0 )) || return 0

    case "$output" in
    raw) fmt:header "BREAKING CHANGES" 3 ;;
    text|md) fmt:header "⚠ BREAKING CHANGES" 3 ;;
    esac

    local hash subject
    for hash message in ${(kv)breaking}; do
      echo " - $(fmt:hash) $(fmt:scope)$(fmt:subject "${message}")"
    done | sort
    echo
  }

  function display:type {
    local hash type="$1"

    local -a hashes
    hashes=(${(k)commits[(R)$type]})

    # If no commits found of type $type, go to next type
    (( $#hashes != 0 )) || return 0

    fmt:header "${TYPES[$type]}" 3
    for hash in $hashes; do
      echo " - $(fmt:hash) $(fmt:scope)$(fmt:subject)"
    done | sort -k3 # sort by scope
    echo
  }

  function display:others {
    local hash type

    # Commits made under types considered other changes
    local -A changes
    changes=(${(kv)commits[(R)${(j:|:)OTHER_TYPES}]})

    # If no commits found under "other" types, don't display anything
    (( $#changes != 0 )) || return 0

    fmt:header "Other changes" 3
    for hash type in ${(kv)changes}; do
      case "$type" in
      other) echo " - $(fmt:hash) $(fmt:scope)$(fmt:subject)" ;;
      *) echo " - $(fmt:hash) $(fmt:scope)$(fmt:type)$(fmt:subject)" ;;
      esac
    done | sort -k3 # sort by scope
    echo
  }

  ##* Release sections order

  # Display version header
  display:version

  # Display breaking changes first
  display:breaking

  # Display changes for commit types in the order specified
  for type in $MAIN_TYPES; do
    display:type "$type"
  done

  # Display other changes
  display:others
}

function main {
  # $1 = until commit, $2 = since commit
  local until="$1" since="$2"

  # $3 = output format (--text|--raw|--md)
  # --md:   uses markdown formatting
  # --raw:  outputs without style
  # --text: uses ANSI escape codes to style the output
  local output=${${3:-"--text"}#--*}

  if [[ -z "$until" ]]; then
    until=HEAD
  fi

  if [[ -z "$since" ]]; then
    # If $since is not specified:
    # 1) try to find the version used before updating
    # 2) try to find the first version tag before $until
    since=$(command git config --get ansible-avd.lastVersion 2>/dev/null) || \
    since=$(command git describe --abbrev=0 --tags "$until^" 2>/dev/null) || \
    unset since
  elif [[ "$since" = --all ]]; then
    unset since
  fi

  # Commit classification arrays
  local -A commits subjects scopes breaking reverts
  local truncate=0 read_commits=0
  local hash version tag

  # Get the first version name:
  # 1) try tag-like version, or
  # 2) try name-rev, or
  # 3) try branch name, or
  # 4) try short hash
  version=$(command git describe --tags $until 2>/dev/null) \
    || version=$(command git name-rev --no-undefined --name-only --exclude="remotes/*" $until 2>/dev/null) \
    || version=$(command git symbolic-ref --quiet --short $until 2>/dev/null) \
    || version=$(command git rev-parse --short $until 2>/dev/null)

  # Get commit list from $until commit until $since commit, or until root
  # commit if $since is unset, in short hash form.
  # --first-parent is used when dealing with merges: it only prints the
  # merge commit, not the commits of the merged branch.
  command git rev-list --first-parent --abbrev-commit --abbrev=7 ${since:+$since..}$until | while read hash; do
    # Truncate list on versions with a lot of commits
    if [[ -z "$since" ]] && (( ++read_commits > 35 )); then
      truncate=1
      break
    fi

    # If we find a new release (exact tag)
    if tag=$(command git describe --exact-match --tags $hash 2>/dev/null); then
      # Output previous release
      display-release
      # Reinitialize commit storage
      commits=()
      subjects=()
      scopes=()
      breaking=()
      reverts=()
      # Start work on next release
      version="$tag"
      read_commits=1
    fi

    parse-commit "$hash"
  done

  display-release

  if (( truncate )); then
    echo " ...more commits omitted"
    echo
  fi
}

# Use raw output if stdout is not a tty
if [[ ! -t 1 && -z "$3" ]]; then
  main "$1" "$2" --raw
else
  main "$@"
fi